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Abstract:

An implantable sensor device for capturing at least one physical,
chemical, biological or physiological parameter in the body of a living
being wearing the sensor device upon contact with the body fluid or
tissue of the same, including a sensor housing, a sensor element that is
accommodated in the sensor housing and has a capturing section, which has
direct contact with the body fluid or the body tissue, or which
internally adjoins a surface or opening section of the sensor housing
that has contact with the body fluid or the body tissue, and a
mechanically acting sensor cleaning device for cleaning the capturing
section of the sensor element and/or the surface or opening section of
the sensor housing adjoining the same.

Claims:

1. An implantable sensor device for capturing at least one physical,
chemical, biological or physiological parameter in a body of a living
being wearing the sensor device upon contact with the body medium of the
same, the sensor device comprising: a sensor housing; a sensor element
that is accommodated in the sensor housing and has a capturing section,
which has direct contact with the body medium; and a mechanically acting
sensor cleaning device for cleaning the capturing section of the sensor
element.

2. The sensor device according to claim 1, wherein the sensor cleaning
device comprises gas bubble generation means, which are designed and
disposed such that gas bubbles are generated in the capturing section of
the sensor element.

5. The sensor device according to claim 2, wherein the gas bubble
generation means comprise a piezo oscillator that is connected to an
ultrasonic generator.

6. The sensor device according to claim 2, wherein the gas bubble
generation means comprise electrochemically acting gas bubble generation
means, which comprise at least one electrode and counter-electrode and a
cleaning current generation device connected to the at least one
electrode and counter-electrode.

7. The sensor device according to claim 2, wherein the gas bubble
generation means are designed to bring about a high-voltage flashover and
comprise at least one electrode and counter-electrode and a cleaning
current generation device connected to the at least one electrode and
counter-electrode.

8. The sensor device according to claim 6, wherein the capturing section
and at least one of the electrodes are disposed in a lumen of the sensor
housing having an opening such that the gas formation brought about by an
electrochemical reaction generates a pressure wave in the lumen, which
propagates through the opening.

9. The sensor device according to claim 7, wherein the capturing section
and at least one of the electrodes are disposed in a lumen of the sensor
housing having an opening such that the gas formation brought about by
the high-voltage flashover generates a pressure wave in the lumen, which
propagates through the opening.

10. The sensor device according to claim 2, wherein the gas bubble
generation means are designed such that they generate gas bubbles having
an average volume of less than 1 ml.

11. The sensor device according to claim 1, wherein the sensor cleaning
device comprises time control means for time-dependent, periodic
activation of the cleaning function.

12. The sensor device according to claim 1, wherein the sensor cleaning
device comprises sensor signal-dependent control means for activating the
cleaning function in response to an abnormal time dependence of the
signals of the sensor element.

13. An implantable sensor device for capturing at least one physical,
chemical, biological or physiological parameter in a body of a living
being wearing the sensor device upon contact with the body medium of the
same, the sensor device comprising: a sensor housing; a sensor element
that is accommodated in the sensor housing and has a capturing section,
which internally adjoins a surface or opening section of the sensor
housing that has contact with the body medium; and a mechanically acting
sensor cleaning device for cleaning the surface or opening section of the
sensor housing adjoining the same.

14. The sensor device according to claim 13, wherein the sensor cleaning
device comprises gas bubble generation means, which are designed and
disposed such that gas bubbles are generated in the surface or opening
section of the sensor housing adjoining the same or are moved over the
capturing section of the sensor element.

17. The sensor device according to claim 14, wherein the gas bubble
generation means comprise a piezo oscillator that is connected to an
ultrasonic generator.

18. The sensor device according to claim 14 wherein the gas bubble
generation means comprise electrochemically acting gas bubble generation
means, which comprise at least one electrode and counter-electrode and a
cleaning current generation device connected to the at least one
electrode and counter-electrode.

19. The sensor device according to claim 14, wherein the gas bubble
generation means are designed to bring about a high-voltage flashover and
comprise at least one electrode and counter-electrode and a cleaning
current generation device connected to the at least one electrode and
counter-electrode.

20. The sensor device according to claim 18, wherein the capturing
section and at least one of the electrodes are disposed in a lumen of the
sensor housing having an opening such that the gas formation brought
about by an electrochemical reaction generates a pressure wave in the
lumen, which propagates through the opening.

21. The sensor device according to claim 19, wherein the capturing
section and at least one of the electrodes are disposed in a lumen of the
sensor housing having an opening such that the gas formation brought
about by the high-voltage flashover generates a pressure wave in the
lumen, which propagates through the opening.

22. The sensor device according to claim 14, wherein the gas bubble
generation means are designed such that they generate gas bubbles having
an average volume of less than 1 ml.

23. The sensor device according to claim 13, wherein the sensor cleaning
device comprises time control means for time-dependent, periodic
activation of the cleaning function.

24. The sensor device according to claim 13, wherein the sensor cleaning
device comprises sensor signal-dependent control means for activating the
cleaning function in response to an abnormal time dependence of the
signals of the sensor element.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims the benefit of co-pending U.S.
Provisional Patent Application No. 61/364,814, filed on Jul. 16, 2010,
which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

[0002] The invention relates to an implantable sensor device for capturing
at least one physical, chemical, biological or physiological parameter in
the body of a living being wearing the sensor device upon contact with
the body medium, which means, in the context of the invention, body fluid
or tissue of the same.

BACKGROUND

[0003] Such sensor devices have been known for quite some time in a
variety of designs primarily as signal transmitters for medical
electronic devices, which are likewise implanted, but also as signal
transmitters for external patient monitoring and have been used
clinically. Particularly common are sensing electrodes for tapping
electric potential in the body, such as heart or other muscle action
potential or cerebral activity. However, non-electric sensors, such as
optical sensors for capturing the blood oxygen saturation, pressure
sensors for capturing the blood and internal vessel pressure,
electrochemical sensors and the like, are also known and used at least
selectively.

[0004] Particularly in the case of non-electric sensor types, during
permanent use, frequently the problem has arisen that the sensor surface
becomes overgrown with endogenous tissue or that denatured proteins from
the surrounding body fluid deposit on the sensor surface. As a result, at
least the sensitivity of the sensor is disadvantageously diminished, and
frequently the functional capability is completely lost and the sensor
becomes unusable.

[0005] As a counter-measure, a variety of coatings for the sensor surfaces
have been developed, which are designed to destroy the biochemical
deposition chain. Furthermore, the approach of "burning off" the
capturing surfaces of sensor arrays designed specifically with respect to
the cleaning function has been pursued. These approaches have proven to
be only conditionally successful.

[0006] The invention is directed at overcoming one or more of the
above-identified problems.

SUMMARY OF THE INVENTION

[0007] It is therefore the object of the invention to provide an improved
sensor device of the type stated above, which in permanent operation has
improved reliability and a longer service life.

[0008] This object is achieved by a sensor device having the
characteristics of the independent claim(s). Advantageous refinements of
the inventive concept are the subject matter of the dependent claims.

[0009] The invention proposes to provide a mechanically acting sensor
cleaning device in the sensor device for cleaning the capturing section
of the sensor element and/or the surface section of the sensor housing
adjoining the same.

[0010] In one embodiment of the invention, the sensor cleaning device
comprises gas bubble generation means, which are designed and disposed
such that gas bubbles are generated in the capturing section of the
sensor element or the surface section of the sensor housing adjoining the
same or are moved over the same.

[0011] This embodiment can be refined in a variety of ways. In one
embodiment, electrothermally acting gas bubble generation means are
provided, which comprise, in particular, a cleaning current generation
device and a conductor means connected thereto. "Conductor means" means,
in the context of the invention, a conductor assembly or a conductive
layer. According to a further embodiment, the gas bubble generation means
comprise an ultrasonic generator, particularly a piezo oscillator that is
connected to an ultrasonic generator.

[0012] In a further embodiment, electrochemically acting gas bubble
generation means are provided, which, in particular, comprise at least
one electrode and counter-electrode and a cleaning current generation
device connected to the same. An embodiment of the gas bubble generation
means has a similar design, wherein the gas bubble generation means are
designed to bring about a high-voltage flashover, or sparkover, and
comprise, in particular, at least one electrode and counter-electrode and
a cleaning voltage generation device connected to the same.

[0013] Both the electrochemically acting and the high-voltage gas bubble
generation devices can advantageously be used in a further embodiment. In
this embodiment, the capturing section and at least one of the electrodes
are disposed in a lumen of the sensor housing having an opening such that
the gas formation caused by an electrochemical reaction or the
high-voltage flashover generates a pressure wave in the lumen, which
propagates through the opening.

[0014] With respect to the avoidance of physiological problems during the
operation of the sensor cleaning device, in a further embodiment the gas
bubble generation means are designed such that they generate gas bubbles
having an average volume of less than 1 ml per cleaning cycle or per day.
Therefore, the maximum cleaning time shall be limited per cleaning cycle
and/or per day to ensure a maximum gas bubble volume of 1 ml considering
cleaning surface and parameters (voltage, current, etc.).

[0015] According to a further embodiment, the sensor cleaning device
comprises time control means for the time-dependent, in particular,
periodic, activation of the cleaning function. As a result, the energy
consumption (which usually places strain on the battery of the sensor
device) of the cleaning processes can be minimized when taking empirical
values into account with respect to the growth time duration of blood
and/or tissue elements. In an alternative variant, or a variant that can
be combined with the above embodiment, the sensor cleaning device
comprises sensor signal-dependent control means for activating the
cleaning function in response to an abnormal time dependence of the
signals of the sensor element. While this latter version requires a
higher implementation complexity, it allows even better adaptation of the
cleaning function to the actual deposition of the sensor surface during
the operation of the sensor device.

[0016] Various other objects, aspects and advantages of the invention can
be obtained from a study of the specification, the drawings, and the
appended claims.

DESCRIPTION OF THE DRAWINGS

[0017] Advantages and functional characteristics of the invention will
additionally become apparent hereinafter from the description of
exemplary embodiments based on the figures. Shown are:

[0018] FIGS. 1A and 1B are schematic illustrations of a passive sensor
implant,

[0019]FIG. 2 is a synoptic illustration to highlight the object to be
achieved by the invention,

[0020]FIG. 3 is a schematic illustration of one embodiment of the
invention,

[0021]FIG. 4 is a schematic illustration of a further embodiment of the
invention,

[0022]FIG. 5 is a schematic illustration of a further embodiment of the
invention,

[0023]FIG. 6 is a schematic illustration of a further embodiment of the
invention, and

[0024]FIG. 7 is a schematic illustration of a further embodiment of the
invention.

DETAILED DESCRIPTION

[0025] FIGS. 1A and 1B show schematic top views of the basic design of a
passive sensor implant or an implantable sensor device 100, comprising a
sensor housing 110, a sensor element 120, and a coil 130 for signal
transmission in connection with a telemetric activation of the sensor and
communication with a telemetry device located outside of the body of a
wearer (not shown). FIG. 1B shows that the sensor is hermetically
enclosed by the sensor housing 110 in the usage state, wherein only a
sensor window or a capturing section 140 that is required for obtaining
the sensor information upon contact with the body fluid or body tissue of
the wearer is not encapsulated.

[0026]FIG. 2 illustrates the problem which arises during long-term use
with such implantable sensor devices in the body of a wearer, and which
has prompted the deliberations of the inventors. A sensor element
illustrated here as a "black box" and denoted with numeral 220 is covered
by a protective layer 221, which is transparent to the sensor information
and which, in turn, has a special surface layer 222 that inhibits the
growth of biological material. However, over the course of
time--symbolized here with a time axis "t"--the endogenous proteins also
degenerate on this special surface 222 and result in deposits 250, which
increasingly encapsulate the sensor element 220 with respect to the body
fluids containing the sensor information, thereby rendering it unusable.

[0027] In a similar illustration as in FIG. 2, FIG. 3 shows the basic
design of a first sensor device 300 according to the invention,
comprising a sensor element 320, which additionally has an electrically
conductive surface 323 over the transparent protective layer 321 and the
growth-inhibiting surface layer 332, and which is likewise transparent to
the sensor information. An electric potential is applied at periodic
intervals to the surface (the capturing section) of the sensor device by
way of a counter-electrode 324 provided at the back of the sensor element
320 and a controllable power source 360. In coordination with the
electric parameters of the electrode layers 322, 324 and the body fluids
typically surrounding the sensor device, this voltage is selected such
that a current flows to the capturing surface which is sufficient to
bring about an electrochemical reaction and the development of gas
bubbles 370.

[0028] During the periodic cleaning processes, the gas bubbles 370 detach
degenerated proteins 350, that have meanwhile deposited, from the
capturing surface. The duration and intensity of the current input is
defined such that a short-term bubble formation takes place over the
entire capturing surface, however, the surrounding body tissue is not
damaged and the gas volume that is generated is physiologically safe.

[0029] As a further embodiment of the invention, FIG. 4 shows a sensor
device 400 which again comprises a sensor element 420 and the usual
transparent protective layer 421, however, in which gas bubble generation
means that function differently than in the first embodiment are
provided.

[0030] In this case, these means comprise a piezo oscillator 425, which is
periodically excited by an ultrasonic generator 460 to oscillate in the
ultrasonic range so as to perform a cleaning cycle. The piezo oscillator
425 is disposed on the surface of the conventional transparent protective
layer 421, and the growth-inhibiting surface coating 422 is disposed on
the piezo oscillator 425 in this case. The ultrasonic vibrations generate
small gas bubbles 470 on the sensor surface, which collapse directly
after they have been produced (see reference numeral 470') and, in the
process, detach proteins 450, that have meanwhile deposited, from the
capturing surface. The mechanism of action of this embodiment of the
invention corresponds at least partially to that of an ultrasonic
cleaning bath.

[0031] In the ultrasonic generator, a control device 480 is provided as a
control device for controlling the cleaning procedures, which in the
simplest case can be designed as a timer, but in a more intelligent
embodiment (illustrated with dotted lines) can be connected on the input
side to the sensor element 420 and capture a degeneration of the sensor
signal, using it as a trigger to start a cleaning process.

[0032]FIG. 5 shows a variant of the invention that is very similar to the
embodiment of FIG. 2, wherein, in terms of the design, basically the
counter-electrode has been eliminated. The remaining parts correspond to
the embodiment of FIG. 3 and are therefore denoted with similar reference
numerals. The surface layer 523 is a conductive layer which is
transparent to the sensor signal and which, when a briefly applied,
relatively high current passes through, heats up so strongly that gas
bubbles 570 form in the surrounding body fluid.

[0033] The further sensor device 600 according to FIG. 6 has a different
mechanism of action. The sensor element 620 thereof has a lumen 626, in
which a capturing section (which is not denoted separately here) of the
sensor element is located, comprising an opening 627, through which the
lumen is in fluid connection with the surrounding body fluids of the
implant wearer. In order to clean this opening on a regular basis, two
electrodes 690 are disposed in the lumen 626, which are connected to a
high-voltage generator 660 and are supplied by the same periodically with
high voltage for the cleaning cycles. The resulting explosive gas
formation generates a considerable overpressure in the lumen 626, as a
result of which denatured proteins 650 clogging the opening 627 are
expelled. In this way, the opening of the sensor element 620 is cleaned
reliably.

[0034] As a modified embodiment of the embodiment described last, FIG. 7
shows a sensor device 700 which has substantially the same design as the
sensor device 600 according to FIG. 6, however, where a different
cleaning mechanism is employed. The gases in the lumen 726 here are
generated by an electrochemical gas formation on one of the two
electrodes 790. The other of the two electrodes can form the required
counter-electrode, however, it is also possible--as is shown additionally
synoptically in the figure--that a counter-electrode 791 is provided
which is located outside of the lumen 726.

[0035] The implementation of the invention is not limited to the concepts
highlighted above and the examples that are described, but is likewise
possible in a plurality of modifications, which are within the scope of
standard practice in the art.

[0036] It will be apparent to those skilled in the art that numerous
modifications and variations of the described examples and embodiments
are possible in light of the above teachings of the disclosure. The
disclosed examples and embodiments are presented for purposes of
illustration only. Other alternate embodiments may include some or all of
the features disclosed herein. Therefore, it is the intent to cover all
such modifications and alternate embodiments as may come within the true
scope of this invention, which is to be given the full breadth thereof.
Additionally, the disclosure of a range of values is a disclosure of
every numerical value within that range.

Patent applications by Marc Hauer, Zuerich CH

Patent applications by Thomas Doerr, Berlin DE

Patent applications by DYCONEX AG

Patent applications in class Measuring or detecting nonradioactive constituent of body liquid by means placed against or in body throughout test

Patent applications in all subclasses Measuring or detecting nonradioactive constituent of body liquid by means placed against or in body throughout test